Chlorinated latex disposable gloves are very common to be used in medical examination procedures.
For example, a questionnaire was shared with 89 general dental practitioners or GDPs in June 2017.[1]
The survey was about their daily use of latex gloves in UK general dental practice.
At the end of this questionnaire, the results showed that most GDPs routinely use non-latex-containing gloves in their clinical dentistry.
This is mainly to avoid latex allergy either among the practitioners themselves or among the patients.
The prevalence of latex allergy and sensitization is currently 9.7% and 12.4%, respectively, among healthcare workers or HCWs globally.[2]
Besides, the average prevalence of latex allergies in the general population worldwide is about 4.3%, according to data analysis from small studies.[2]
Therefore, manufacturers had to search for a proper solution.
Mainly because of the difference between the price of latex gloves and other non-latex disposable gloves.
For this reason, a new version of a low protein latex examination glove has emerged on the market.
This powder-free glove has unique features and different methods to be produced by the factory.
Glove Chlorination is one of the standard procedures to get that low protein latex powder-free glove.
So, in this article, you will find a brief explanation of the process of chlorination and other finishing methods in manufacturing gloves.
So, all you need to do is relax and read slowly.
Hopefully, you will find it enjoyable.
What is Glove Chlorination?
Chlorination is a finishing method for disposable gloves to remove excess powder and reduce friction when wearing the gloves.
It is a process where the gloves are dipped into a diluted aqueous chlorinated solution and other chemicals during manufacturing.
This starts with prewashing powdered latex gloves to remove excess powder and transfer them into powder-free gloves.
After that, neutralization and further washing are performed to remove surface residues.[3]
In general, residual extractable protein or EP levels have been significantly decreased in latex gloves and other products that have been chlorinated.
But, what exactly is happening in this process?
How is Glove Chlorination achieved?
This chlorination cleans the glove’s powder surface and breaks down latex protein and other chemical residues.[4]
It starts with preparing chlorine solutions at concentrations of 500, 1000, and 2000 ppm (parts per million of chlorine).
Then, a mixture of the following:
- Sodium hypochlorite or NaClO
- Hydrochloric acid or HCl
- Water or H2O
- Sodium thiosulphate or Na2S2O3
That mixture is created into the desired concentration and placed in large plastic containers where the gloves can be immersed.
The gloves were then dipped in the aqueous chlorine solutions for 10 minutes.
Following the chlorination process, the gloves are rinsed with a neutralizer solution for 5 min at 60 degrees C with water.
Afterward, the gloves are dried for 5 min at 100–120 degrees C before being removed from the former.
Because of this procedure, as we previously said, most of the latex proteins are removed.
Double Chlorination
Chlorination at room temperature can boost the elimination of nitrosamine and nitrosatable components of natural rubber gloves.
The reduction for double-surface gloves was more significant than for ingle-surface chlorinated gloves.
Double-chlorinated gloves are needed, especially for medical applications.
These gloves are chlorinated on internal and external surfaces during this process.
For this reason, Double-chlorinated gloves emerged as they are produced with second chlorination.
Gloves after the earlier chlorination are immersed again into another chlorine tank before the final drying stage.
Besides, single-chlorinated gloves have a significant disadvantage: the outer surface of a single-chlorinated glove is not treated with chlorine.
Thus, such gloves tend to stick to each other.
This characteristic prevents the process of double gloving, which is the wearing of two layers of gloves, one on top of the other, to increase protection among medical personnel.
Please take a quick look around the market; almost every brand promotes its products by mentioning the double chlorination process.
Furthermore, in comparison to the leaching process of the rubber glove at room temperature, the chlorination procedure can remove much more nitrosamine and nitrosatable substances from the glove.
But why is it important to do all these steps?
What is the effect of chlorination?
The powdered gloves are much easier to wear and unwear because of the powder inside them.
For this reason, manufacturers tried to overcome this in non-powder gloves by chlorination.
Moreover, chlorination is used to reduce the tackiness of latex film surfaces of gloves to improve the ease of donning, as we stated, without adding lubricating powders.
Besides, extra washing during the chlorination process provides an additional benefit by significantly reducing the level of soluble latex proteins in latex gloves.
This act makes the glove smoother yet firmer.
For these reasons, high-quality household gloves and many other domestic products are usually used.
When chlorine comes into contact with a natural rubber product, it reacts with every surface molecule to build a structure that limits the rubber’s access to oxygen or ozone in the future and raises its resistance to absorbing oils and greases.
But mainly, the most crucial goal is to make them less likely to cause an allergy.
Disadvantages of Chlorination
The chlorination procedure also may alter the grip properties of the glove’s outer surface.
Mainly, there is a possible disadvantage that chlorination slightly reduces the shelf life of products.
Of course, keep in mind that the chemicals break down the glove material.
Another potential drawback is price.
Chlorinated gloves or powder-free gloves are more expensive than other usual disposable latex gloves.
There is another problem as the chlorinated latex will take on the unmistakable odor of chlorine.
For this reason, some customers may refuse to purchase those gloves.
Then, are there other finishing procedures for gloves, such as chlorination?
Other Finishing Glove Steps
Many manufacturers are working hard to cut the protein content of their products to an acceptable level.
Therefore, new and improved technologies are now available to achieve this.
This includes the following:
- Chlorination ( powder-free ).
- Polymer coating ( powder-free ).
- Chemical or enzymatic deproteinization.
- Use of low-protein latices (especially processed non-synthetic or natural latices ).
- Proper optimized and leaching process.
In this part of the article, we will briefly discuss each.
-
Polymer coating
Polymer coating provides an alternative way to reduce the surface tackiness of powder-free latex gloves.
A chemical process occurs during polymerization to transform monomer molecules into polymers.
Notably, applying a polymer coating is a more recent method; it also helps to replace powder as the donning lubricant.
The process involves coating glove surfaces with a polymer such as hydrogels, silicone polymer, polyurethane, acrylics, and nitrile, among other blends.
Furthermore, a dual approach is often processed:
- Coating of the donning side.
- Chlorination of the gripping side of the glove.
Not only polymer coating is used on Latex gloves but also Nitrile gloves. Some other disposable gloves even feature a double polymer coating.
This coating is preferred on the interior side of gloves, making them easy to take on and off.
Nitrile gloves retain their odor neutrality and color consistency when a double polymer coating is applied to the interior.
When choosing between disposable gloves with a double polymer coating and gloves that have undergone the chlorination process, the double polymer coating appears to be the better option.
-
Chemical or Enzymatic deproteinization
This technique involves dipping latex gloves in proteolytic enzyme solutions while processing under the proper circumstances instead of treating raw latex to remove the broken-down protein in the serum phase.
Moreover, the colloidal stability of the latex must be maintained in such preparation by an appropriate stabilizing mechanism, which often involves a surfactant.
The enzyme is crucial in breaking down large protein molecules into manageable pieces for processing removal.
However, it has been noted that the mechanical properties and stability of these “low protein latex” are unpredictable and occasionally worse.
The method is suitably applied to producing natural rubber products such as rubber gloves, a condom, a catheter, and foam rubber material.
-
Low-protein latices
It is another process that is used for latex deproteinization.
The preparation of low-protein latices involves the reduction of proteins during the liquid latex stage or removal at the source.
There are numerous treatments, but enzymatic treatment and physical means are the two that are frequently used.
Firstly, physical means where latex concentrate ( either raw or prevulcanized ) is diluted and re-centrifuged further to eliminate the soluble proteins in the serum phase.
Secondly, an enzymatic treatment where latex concentrate is treated with a proteolytic enzyme, after which the treated latex is also centrifuged to remove the broken-down protein in the serum phase.
A suitable stabilizing mechanism is needed to keep the latex microparticles stable in such a formulation, which often involves a surfactant.
The latex could produce low-grade film products if left in an unstable state.
-
Leaching protocol
This leaching phase can be called pre-vulcanization leaching.
The term wet gel leaching is also known as it.
A longer leaching process can wash out residual chemicals and latex protein on the top of gloves more effectively.
Additionally, for the protein to dissolve more efficiently, the water in the inflatable must be hot and fresh.
This step is essential to lowering the severity of latex sensitivity.
Significantly, studies have shown that residual proteins on the surface of the gloves are concentrated on the donning side.
The soluble proteins mainly cause this in the wet latex film during production.
This starts when latex gloves are first leached during the wet-gel stage and continues throughout the curing and drying processes in the vulcanization ovens.
For this reason, leaching is preferred in both the wet-gel/pressure stage and after the drying/posture stage for a confirmatory method of removal of the remaining proteins.
Finally, good leaching lines can result in a good and high-quality latex glove.
Conclusion
The thick or thin gloves each have issues when being donned by the customers.
The mentioned choices in this article are all customized to specific users, activities, and preferences.
Notably, donning the gloves was found quicker with chlorination even when there is little to no moisture on the hands.
The finishing glove process, particularly chlorination, also makes the glove softer for people who need to work with their hands all day.
Additionally, these procedures minimize the latex proteins that cause allergies and inflammation.
If chlorination and polymer coatings are done correctly, these procedures create gloves that go beyond FDA requirements for hand protection.
However, adding extra components to gloves’ typical composition can be pricey compared to the basic possibilities.
But, there is no exact answer to which glove option is best for you.
Each one has its pros and cons.
Therefore, scientists and manufacturers work hard to achieve the most benefit from their goods.
Generally, double chlorination is the most popular procedure among the creators.
This does not mean that other finishing steps and methods are not as crucial as chlorination.
Simply put, finishing makes wearing disposable gloves easier and more comfortable.
